The advent of higher speeds and higher load carrying capacities in the jet aircraft of today are creating a demand for longer and longer runways capable of withstanding more impact forces and more dead rolling weight forces than ever before. To find room for such, airports are being constructed increasingly far from the centers of population to provide increasingly inconvenient service at increasingly greater expense.
Furthermore, such larger and faster aircraft cannot be used to provide service near cities not able to provide suitable landing and takeoff facilities.
Flight paths for normal takeoff and landing of today's jet aircraft carry them for long distances in alignment with the runways and, consequently, tend to carry them over large centers of population thus increasing the air pollution and certainly the noise pollution over those centers. Suggested solutions include sharply increasing the angle of takeoff and landing flight paths, thus increasing the chances for accident; restricting takeoff and landing patterns to one or two runways, thus necessarily forcing landings in dangerous cross winds at times; restricting landing and takeoff times to times when the majority of the population is not asleep; and moving the airport sites even farther from the metropolitan centers.
It has been proposed to provide aircraft which can take off vertically and then can be adapted for horizontal flight from place to place, again being capable of vertical landing when the destination has been reached. See, for example, U.S. Pat. No. 2,959,373 to Zuck, granted Nov. 8, 1960; U.S. Pat. No. 1,620,787 to Thomas, granted Mar. 15, 1927; U.S. Pat. No. 2,674,421 to DeCenzo, granted Apr. 6, 1954; U.S. Pat. No. 2,187,295 to Alvistur, granted Jan. 16, 1940; U.S. Pat. No. 2,628,792 to Griffith, granted Feb. 17, 1953; U.S. Pat. No. 3,514,051 to Celayan, granted May 26, 1970; and U.S. Pat. No. 2,008,843, to Smith, granted July 23, 1935. See also Belgium Pat. No. 507,343 to Mignot, granted in May of 1954.
These patents represent everything from very carefully thought theoretical applications to outright wild schemes; and none have found practical or commercial acceptance.
Other suggestions for obtaining vertical landings and takeoffs include circular, whirling wing flying craft such as shown in U.S. Pat. No. 3,199,809 to Modesti, granted Aug. 10, 1965.
In order to reduce the horizontal drag on vertical landing and takeoff aircraft during horizontal flight, it has been suggested to have the helicopter rotor blades fold back into a trailing position. See U.S. Pat. No. 2,424,769 to Page, granted July 29, 1947; U.S. Pat. No. 3,771,924 to Buchstaller, granted Nov. 13, 1973; and U.S. Pat. No. 2,687,779 to Peterson, granted Aug. 31, 1954.
Most of these patents apparently disclosed schemes which were at least theoretically workable, but none have met with commercial acceptance.
It has been suggested to power the rotor blades of a helicopter using the jet or rocket reaction principle. See U.S. Pat. No. 3,010,678 to Gose, granted Nov. 28, 1961; U.S. Pat. No. 2,437,700 to MacFarland, Jr., granted Mar. 16, 1948; and the above mentioned patents to DeCenzo; Celayan; Mignot; and Peterson. See also U.S. Pat. No. 3,558,082 to Bennie, granted Jan. 26, 1971.
It is common to provide some kind of a swash plate arrangement around the outside of a central rotor drive shaft to cause a cyclic motion of the rotor blades along this longitudinal axis to effect the desired direction of a horizontal component of motion through the air; but such systems have lacked an effective, safe and inexpensive means for simultaneously varying the average pitch angle of attack of all of the rotor blades to obtain varying lift speeds or to maintain hovering. See French Pat. No. 1,479,854 to Wagner, dated Mar. 19, 1967; U.S. Pat. No. 2,162,794 to Von Asboth, granted June 20, 1939; U.S. Pat. No. 2,414,435 to Bendix, granted Jan. 21, 1947; U.S. Pat. No. 2,364,096 to Platt, granted Dec. 5, 1944; U.S. Pat. No. 2,629,567 to Papadakos, granted Feb. 24, 1953; U.S. Pat. No. 2,474,362 to Keranen, granted June 28, 1949; and U.S. Pat. No. 2,950,074 to Apostolescue, granted Aug. 23, 1960.
Other patents which appear to present pertinent features of the prior art include U.S. Pat. No. 3,698,666 to Monti, granted Oct. 17, 1972 and U.S. Pat. No. 2,192,300 to Droitcour, granted Mar. 5, 1940.